Dicer is a large multi-domain enzyme responsible for cytoplasmic production of both microRNAs (miRNAs) and short interfering RNAs (siRNAs) during sequence-directed gene regulation by RNAi. As a member of the Ribonuclease III family of proteins, Dicer recognizes the 5′ and 3′ helical ends of double-stranded RNA substrates and cleaves a specific distance away to produce 21-27 nucleotide products. Dicer helps these mi- and siRNAs to load onto Argonaute proteins together with other protein components of the RNA-induced silencing complex (RISC). Once bound to target mRNAs, miRNAs typically regulate protein expression by controlling the level of translation, whereas siRNAs direct cleavage and subsequent degradation of complementary mRNAs.
Production of siRNAs is useful in various research and therapeutic applications. There is a need in the art for an enzyme that efficiently generates siRNAs from a double-stranded RNA substrate.